It is important for manufacturing lines which process strip material, such as steel, to operate continuously for at least an entire day or work shift. The strip material is usually coiled and positioned on an uncoiling device which is rotatable to pay off the strip to the processing line. In order to render the system continuous, usually a strip accumulating device, such as that shown in U.S. Pat. No. 3,506,210, is provided between the uncoiler and the processing line to store a sufficient quantity of strip therein so that the operator has time to weld the trailing end of the strip just depleted to the leading end of a new coil of strip positioned on the uncoiler.
This type of system has been very popular and successful but the cost thereof is often not economically justified for certain applications, such as processing lines operating at low speeds. The strip accumulators, in order to hold sufficient quantities of strip, often have to be quite large taking up much floor space. In addition, by utilizing the system just described, a welder must be positioned on-line between the uncoiler and accumulator so that the coils can be attached, and an operator must almost always be present. This too adds to the cost of the system. Furthermore, accumulators are not always workable with certain types of strip material. For example, many accumulators will not satisfactorily handle light gauge strip material or narrow strip material. Nor will they operate at high speeds without marking or otherwise damaging certain types of strip material. Finally, using these types of accumulators often requires that the trailing end of a coil just depleted be welded very quickly to the leading end of a new coil often resulting in poor welds or at least requiring an expensive end welder to assure a good weld.
None of the attempts to eliminate the need for accumulators or provide a suitable substitute therefor have been successful or practical. Of course, one huge coil could be provided which could carry a day's supply of strip but such would be so large and cumbersome that it could create more problems than it would solve. Because this would involve a time consuming and costly coil build-up operation, such large coils are not presently even commercially available.
U.S. Pat. No. 4,022,396 suggests that smaller coils could be stacked and interconnected but the device disclosed therein is not practical for many strips and most processing lines. There, the method of connecting and stacking the coils of strip puts undue stresses on all but the most flexible and thinnest of strips. Further, there is no suitable way disclosed in the patent to pay the vertically oriented strip off to the horizontally oriented processing line. Nor has any device been developed to adjust the height of the pay off to the processing line as strip is drawn from successive coils. The processing line must receive strip at a constant location, that is, a constant height. Only by placing the device of U.S. Pat. No. 4,022,396 a long and impractical distance from the processing line could this be accomplished. But most manufacturing facilities cannot afford to use that much floor space to accomplish this function. Finally, no one has developed any means to account for the varying tangential speeds at which the coil is payed out as one interconnected coil becomes depleted at a small diameter and a high rotational speed and quickly must slow down as coil is payed out from the outer diameter of a new coil at a considerably lower rotational speed.
In short, no one has developed a suitable substitute for the costly accumulator system which will operate as efficiently to continuously provide strip material to a processing line.